The present invention relates to a vibrating conveyor which has a frame, a conveying element which is arranged to carry objects to be conveyed and is mounted on the frame to be moved back and forth between a first end position and a second end position, and a drive means arranged in the frame to move the conveying element back and forth, the drive means being arranged to move the conveying element relatively slowly to the first end position, and to move it relatively fast to the second end position, thereby bringing about a displacement of the objects in a direction corresponding to the moving direction of the conveying element from the second end position to the first end position.
In the engineering industry there are often problems in moving objects from a working position to a take-up position, or to another working position if the space is limited. It is thus difficult, if not impossible, to install an effective roller or belt conveyor in connection with eccentric presses or the like and, therefore, the objects often have to be moved manually. Experiments have been made with vibrating conveyors which, however, have the disadvantage of suddenly changing conveying direction, which means that the objects can be returned to the working position and thus cause damage. Besides, vibrating conveyors operate at a very high noise level.
These problems have been eliminated using a vibrating conveyor of the type described by way of introduction and known from Swedish patent specification 7702895-9 (Publication No. 414,160). In this known vibrating conveyor, the drive means comprises a pneumatic piston and cylinder assembly and a relatively complicated arrangement of springs and valves in order to have this known vibrating conveyor operate in a satisfactory way, it is required that the drive means contain lubricating oil for the parts that are movable in relation to each other. The compressed air used for driving causes oil in this known vibrating conveyor to be ejected from the interior of the conveyor and to contaminate the conveyor as well as the surroundings.
The object of the present invention is thus to provide a vibrating conveyor, in which this disadvantage is eliminated and which moreover has a considerably simpler structure than the known vibrating conveyor.
According to the invention, this object is achieved by a vibrating conveyor which is of the type stated by way of introduction and is characterised in that the drive means has a cam wheel which is rotatably arranged in the frame and which on its periphery has at least one cam with a cam surface which has a distance to the centre of the cam wheel that increases continuously in the direction opposite to the direction of rotation or the cam wheel, and which is terminated abruptly with a substantially radially directed cam surface portion, that the drive means further has a spring member arranged in such manner between the frame and the conveying element that it is tensioned during the movement of the conveying element to the first end position, and then moves the conveying element from the first end position to the second end position, and that the conveying element has a cam following means connected thereto, which abuts against the periphery of the cam wheel to follow the cam surface of the cam or cams as the cam wheel rotates and move the conveying element to the first end position against the action of the spring member.
Preferably, the cam wheel has four identical cams uniformly distributed along the periphery or the cam wheel.
In a preferred embodiment each cam surface has a distance to the centre of the cam wheel which first increases slowly and then faster and faster to give the conveying element a gradually increasing acceleration when moving from the second end position to the first end position.